The present invention relates to polysilicon resistors used on semiconductor chips. Polysilicon resistors are strips of polysilicon doped with a material, such as phosphorus, to be made more conductive. Polysilicon resistors have a certain sheet resistance, which is a resistance per "square" which depends on the thickness of the polysilicon resistor. Polysilicon resistors are formed to have a fixed resistance determined by the number of squares that comprise the resistor. Polysilicon resistors have uses in circuits such as analog to digital converters.
It is desired to reduce the variation in the resistance value of the polysilicon resistors for different voltages across the resistor. If this variation of the polysilicon resistors value can be reduced, a more accurate analog-to-digital and digital-to-analog conversion can occur.